我們有一個運行 8 個 CPU 核心的 16 GB linode，我正在嘗試調試一個問題，當我嘗試負載測試時，伺服器開始在一個非常基本的 WordPress 網站上每秒發出大約 250 個請求。我只是點擊了該網站的首頁僅供參考。
當我登入伺服器並在 Htop 上查看伺服器統計資料時，我看到所有核心都已固定，並且 php5-fpm 進程的垃圾負載。測試完成後，這些進程仍然存在，我最終必須重新啟動 php-fpm 才能使伺服器恢復正常。
今天做負載測試時在日誌中看到了這一點。
[23-Dec-2013 12:19:03] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 0 idle, and 27 total children
[23-Dec-2013 12:19:04] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 16 children, there are 0 idle, and 35 total children
[23-Dec-2013 12:19:05] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 32 children, there are 0 idle, and 45 total children
[23-Dec-2013 12:19:06] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 32 children, there are 0 idle, and 55 total children
[23-Dec-2013 12:19:07] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 32 children, there are 0 idle, and 65 total children
[23-Dec-2013 12:19:08] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 32 children, there are 0 idle, and 75 total children
[23-Dec-2013 12:19:19] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 5 idle, and 93 total children
很明顯，有些東西是 fubar，我只是不是調整我們目前系統的這些設定的專家。
這是我們的 www.conf
; Start a new pool named 'www'.
; the variable $pool can we used in any directive and will be replaced by the
; pool name ('www' here)
[www]
; Unix user/group of processes
; Note: The user is mandatory. If the group is not set, the default user's group
; will be used.
user = www-data
group = www-data
; The address on which to accept FastCGI requests.
; Valid syntaxes are:
; 'ip.add.re.ss:port' - to listen on a TCP socket to a specific address on
; a specific port;
; 'port' - to listen on a TCP socket to all addresses on a
; specific port;
; '/path/to/unix/socket' - to listen on a unix socket.
; Note: This value is mandatory.
listen = /var/run/php5-fpm.sock
; Set listen(2) backlog. A value of '-1' means unlimited.
; Default Value: 128 (-1 on FreeBSD and OpenBSD)
listen.backlog = 65536
pm = dynamic
; The number of child processes to be created when pm is set to 'static' and the
; maximum number of child processes when pm is set to 'dynamic' or 'ondemand'.
; This value sets the limit on the number of simultaneous requests that will be
; served. Equivalent to the ApacheMaxClients directive with mpm_prefork.
; Equivalent to the PHP_FCGI_CHILDREN environment variable in the original PHP
; CGI. The below defaults are based on a server without much resources. Don't
; forget to tweak pm.* to fit your needs.
; Note: Used when pm is set to 'static', 'dynamic' or 'ondemand'
; Note: This value is mandatory.
pm.max_children = 150
; The number of child processes created on startup.
; Note: Used only when pm is set to 'dynamic'
; Default Value: min_spare_servers + (max_spare_servers - min_spare_servers) / 2
pm.start_servers = 20
; The desired minimum number of idle server processes.
; Note: Used only when pm is set to 'dynamic'
; Note: Mandatory when pm is set to 'dynamic'
pm.min_spare_servers = 10
; The desired maximum number of idle server processes.
; Note: Used only when pm is set to 'dynamic'
; Note: Mandatory when pm is set to 'dynamic'
pm.max_spare_servers = 35
; The number of seconds after which an idle process will be killed.
; Note: Used only when pm is set to 'ondemand'
; Default Value: 10s
;pm.process_idle_timeout = 10s;
; The number of requests each child process should execute before respawning.
; This can be useful to work around memory leaks in 3rd party libraries. For
; endless request processing specify '0'. Equivalent to PHP_FCGI_MAX_REQUESTS.
; Default Value: 0
pm.max_requests = 500
pm.status_path = /status-www
; The log file for slow requests
; Default Value: not set
; Note: slowlog is mandatory if request_slowlog_timeout is set
;slowlog = log/$pool.log.slow
slowlog = /var/log/php-fpm-slow.log
; The timeout for serving a single request after which a PHP backtrace will be
; dumped to the 'slowlog' file. A value of '0s' means 'off'.
; Available units: s(econds)(default), m(inutes), h(ours), or d(ays)
; Default Value: 0
request_slowlog_timeout = 115s
; The timeout for serving a single request after which the worker process will
; be killed. This option should be used when the 'max_execution_time' ini option
; does not stop script execution for some reason. A value of '0' means 'off'.
; Available units: s(econds)(default), m(inutes), h(ours), or d(ays)
; Default Value: 0
request_terminate_timeout = 120s
; Set open file descriptor rlimit.
; Default Value: system defined value
rlimit_files = 65536
; Set max core size rlimit.
; Possible Values: 'unlimited' or an integer greater or equal to 0
; Default Value: system defined value
rlimit_core = 0
對 www.conf 有什麼建議或需要指出的嗎？
答案1
首先，您確實應該問自己一個問題：您的網站真的應該能夠處理每秒 250 個請求嗎？這是對頁面的大量請求。坦白說，我認為考慮到您所擁有的虛擬化系統，CPU 達到 250req/s 的速度是正常的。
pm.max_children = 150
您可能不斷提出這個問題，因為您不斷收到錯誤訊息，表示您對孩子的照顧已經超出了限度。但當你把這個問題提高到超出你的系統可以處理的範圍時，你實際上是在搬起石頭砸自己的腳。不接受它無法處理的下一個請求比接受更好。增加這個值不僅會削弱您的系統，還會產生更多的資源需求和更多的開銷。當它爆炸到你的系統無法再處理的大小時，它會產生諸如凍結之類的跡象。我不確切知道您的VPS 為您提供了什麼（您永遠不會知道，因為它不是靜態的，因為它取決於節點中的其他用戶），但我個人認為，對於您指定的系統，任何超過20的值都不是現實的設定。
您還應該相應地調整開始/最小/最大備用，因為大於最大子項是沒有意義的。或者您可以不擔心它並設置為pm = static。
答案2
將流程管理改為隨選管理
pm = ondemand